In most documents, the number of tags that fit in a screenful completely dwarfs the number of tags that don't. So it makes sense to optimize for the former case

In most documents, the number of tags that fit in a screenful completely dwarfs the number of tags that don't. So it makes sense to optimize for the former case. And I don't think forcing redundance everywhere is a proper way to "make it 'easier' to edit". You seem to worry about counting closing parentheses but with s-expressions you don't count parentheses. You just look at indentation and the structure emerges. I just don't buy the "XML should be writable without a proper editor" argument. Why optimize for the couple clueless fools that will try to edit it in NotePad if it hampers the work of the tons of people who actually need to edit lots of XML and actually use a proper editor? Using a proper editor also fixes the undirected quotes problem. Besides, s-expressions might even work better than XML in NotePad because you don't have to indent the end tag because it's just a closing parenthesis that you don't indent.